docs: def write_txt(matrix, version, out, border=None, color='1', background='0'):
      """\
      Serializes QR code in a text format.
  
      :param matrix: The matrix to serialize.
      :param int version: The (Micro) QR code version
      :param out: Filename or a file-like object supporting to write text.
      :param int border: Integer indicating the size of the quiet zone.
              If set to ``None`` (default), the recommended border size
              will be used (``4`` for QR Codes, ``2`` for a Micro QR Codes).
      :param color: Character to use for the black modules (default: '1')
      :param background: Character to use for the white modules (default: '0')
      """
      row_iter = matrix_iter(matrix, version, scale=1, border=border)
      colours = (str(background), str(color))
      with writable(out, 'wt') as f:
          write = f.write
          for row in row_iter:
              write(''.join([colours[i] for i in row]))
              write('\n')